Put a pizza stone or upside-down baking sheet in the oven; preheat to 500 degrees F. Stretch the pizza dough into a 12-inch round on a floured surface. Dust a pizza peel or upside-down baking sheet with 1/2 teaspoon cornmeal and put the dough on top. Brush with the olive oil and sprinkle with the sugar and the remaining 1/2 teaspoon cornmeal. Slide onto the hot pizza stone or baking sheet and bake until golden on the bottom, 5 to 7 minutes.
Meanwhile, mix the mashed potatoes with 1/4 cup cheese and the milk in a bowl; set aside. Roll tablespoonfuls of the stuffing into 1-inch balls to look like meatballs. Shred the turkey meat and julienne the skin.
Slide the crust back onto the peel. Spread the cheddar mashed potatoes over the crust, then top with the shredded turkey. Spoon the cranberry sauce over the pizza and drizzle with the gravy. Arrange the stuffing balls on top and sprinkle with the remaining 1/4 cup cheese and the turkey skin.
Return the pizza to the oven and bake until golden brown, 8 to 10 more minutes.